Key message: When CT scan shows a pancreatic or periampullary cancer that looks like it can be removed by surgery, having diagnostic laparoscopy may decrease the rate of unnecessary surgery by giving more information about whether this is likely to be so.

Surgery is generally thought to be the only treatment that can cure pancreatic cancer but only about one in five patients have surgery, as in many cases the person is considered to be unfit for major surgery or a CT (computed tomography) scan has shown that the cancer has spread. A CT scan is used to ‘stage’ the disease (this is a means of defining how far a disease has progressed) but despite this as many as a quarter of patients then have a laparotomy, surgery to open up the abdomen and remove the cancer (called a ‘resectable cancer’ if it can be removed), only to find that the cancer can’t all be cut out as hoped (unresectable cancer). The new Cochrane review tells us that diagnostic laparoscopy may enable doctors to more accurately diagnose which patients have resectable cancers and so reduce the number of people who have an unnecessary laparotomy.

Diagnostic laparoscopy involves putting a telescope into the abdomen through a small cut, to look at the organs and to take a sample of the diseased tissue, which can then be examined in the laboratory. There is currently no standard procedure for diagnosing pancreatic cancer and periampullary cancers (which include cancer of the head and neck of the pancreas and part of the bile duct and duodenum) but most people will have a CT scan and this may be the only test before they have a laparotomy, though other tests, such as MRI scan, may be used.

What’s the evidence?

The review team looked for evidence on the effectiveness of diagnostic laparoscopy as an add-on test to the CT scan to find which patients had resectable cancers and which had unresectable cancers. Diagnostic laparoscopy was considered positive if the cancer was unresectable, with cancer spread confirmed by laboratory examination of a tissue sample (paraffin section was the ‘gold standard’ test used). If the sample was negative (or if the results of diagnostic laparoscopy couldn’t be interpreted), the patient went on to have a laparotomy. The cancer was then found to be resectable (a true negative result – the diagnostic test correctly identified a resectable cancer) or unresectable ( a false negative result – the diagnostic test result was wrong, as it indicated a resectable cancer that was found to be unresectable). The reviewers found 15 studies with 1015 patients which could help answer their question; results were combined in a meta-analysis. Here’s what they found:

Adding diagnostic laparoscopy to CT scanning reduces the likelihood of unresectable cancer from 40% to 17%. This means that for every 100 people who have CT plus diagnostic laparoscopy, 23 people will avoid laparotomy compared to CT scanning alone.

How good was the evidence?

The results are based on low quality studies and in particular there are concerns about selection bias as it wasn’t clear how patients were chosen and whether patients were inappropriately excluded

There were lots of differences between studies and some poor reporting. However, diagnostic laparoscopy appeared to reduce the number of unnecessary laparotomies in 14 of the 15 studies

Inappropriate delay between laparoscopy and laparotomy can result in patients who had resectable cancer developing unresectable cancer.This will underestimate the accuracy of diagnostic laparoscopy

Reliance on the surgeon’s judgement that a cancer is unresectable at laparotomy could cause an error in the estimation of diagnostic accuracy

So where does that leave us?

The reviewers conclude that, despite the shortcomings of the evidence, diagnostic laparoscopy appears to be useful in avoiding unnecessary laparotomies, and there is a low risk of complications from the procedure. Cost-effectiveness needs to be formally assessed to help decide whether it should be offered routinely in state funded health systems like ours.There is a need for further well-designed studies to reliably estimate the accuracy of diagnostic laparoscopy and comparison with other tests for staging pancreatic and periampullary cancers.

For those wanting to read more about sensitivity and specificity and sort out their true and false positives and negatives, there’s a good blog on this topic on the Students for Best Evidence website here.

About Sarah Chapman

Sarah's work as a Knowledge Broker at Cochrane UK focuses on disseminating Cochrane evidence through social media, including Evidently Cochrane blogs, blogshots and the ‘Evidence for Everyday’ series for nurses, midwives, allied health professionals and patients.
A former registered general nurse, Sarah has a particular interest making evidence accessible and useful to practitioners and to others making decisions about health. Before joining Cochrane, Sarah also worked on systematic reviews for the University of Oxford and the Royal College of Nursing Institute, and obtained degrees in History from the University of Oxford and in the history of women’s health and illness in early modern England (MPhil., University of Reading).

Take a look: avoiding unnecessary surgery in pancreatic cancer by Sarah Chapman

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